Alternating Current (AC) circuits comprising inductive loading contain stored energy that, when the circuit is switched off, needs to be dissipated. If this stored energy is not accounted for in the design of the circuit, the result could be a number of undesired effects on the circuit and/or the circuit's surrounding environment.
One undesired effect on the circuit can be the build-up of heat in a circuit. For example, circuitry utilized in a switching device may heat up. This may result in requiring a designer to include a heat sink for a switching device. The addition of a heat sink may add cost to a design.
Another undesirable effect on a circuit with stored inductive energy is that the switching-off of the circuit could result in large discharge transients being dissipated throughout the rest of the circuit. These large discharge transients may cause damage to other circuit elements that absorb the energy of the discharge transients.
Yet, another undesired effect may be radio frequency (RF) emissions over a desired level. Various jurisdictions classify devices and limit the types of devices that can be sold. For example, in the United States, the FCC certifies devices as “Class A” or “Class B” depending on the amount of RF energy that the device emits. “Class B” devices are authorized for home use whereas “Class A” devices are limited to office use.